Am I doing something wrong as BLM?

[Aikaal]

Starting rotation (Can use it when you have CDs up):

F3 > Raging Strikes > T2 > Potion > F1 > F1 > F1 > F1 (Use procs) > Swiftcast > Flare > Convert

Regular rotation

T2 > F3 > F1 (Til 300-400 mana) > B3 > T1/T2 (Depending how much mana left you have) > Scathe/B1* > F3 and repeat...

*If you have a slow first mana tick
> Scathe/B1 (Blizzard 1 if you don't have to more, Scathe if you need to move)

There's few tricks to up your DPS in LeviEx. T2 ANY possible target (Tail include! You will take some damage but you dot still hit) More Thunders = more procs.
When Spumes are up, I always save the rest of my mana to Flare the Spume next to Leviathan's head.

If you are caught in a bad position, use Aetherial Manipulation.

Try to save Swiftcast when Levi hits the boat to refresh Thunder 2 (I use Thunder 3 on swiftcast)

**EDIT

When spumes spawn, I make sure to cast F1 > T2 > T2 > F1 > T2 > T2 to gett my stacks. Having high numbers is pretty hard in LeviEx, there are a lot of down time but you have multiple occasions to abuse of Flare. Each time you have two targets close, you can Flare.

[Shadowzanon]

snip

Pretty much this but ill add some more. If its the case you dip to low on mana when casting bliz 3, follow up with bliz 1 before casting t1 or t2 be aware just how much mana you will have left after you're last fire 1. Many blm make the huge mistake of dipping to low on mana then actually waiting for mana to come back to cast t2 you should never be waiting for mana. Mana potions are also used for situations like this. If you ended up with less than 200 mana before casting Bliz 3, use a pot to recover instead of waiting for mana to cast another spell.

You should never be saving raging strikes ever, pop it on cd and if its the case its used when new adds spawn, use quelling strikes together with it.